A number of potent antimalarial compounds cannot be used pharmaceutically because of their accompanying phototoxicity. This is particularly true for a number of compounds structurally related to quinine. The primary goal of this research is to discover the cause of this phototoxicity. Accordingly, the photochemical reactivity of a number of substituted quinolinemethanols of known antimalarial activity will be investigated. After elucidating the products of photolysis of each of these compounds, the mechanisms actually utilized will be contrasted with the corresponding photochemical behavior of the non-phototoxic compounds. In this manner, it is expected that correlations can be drawn between the structure of the compounds and their degree of phototoxicity. Once these structural correlations can be made, guidelines can be established for the necessary structural features for new, synthetic antimalarials which will not have the undesired accompanying phototoxicity.